Electronic structure of the complex hydrideNaAlH4

Abstract

Density-functional calculations of the electronic structure of the complex hydride ${\mathrm{NaAlH}}_4$ and the reference systems NaH and ${\mathrm{AlH}}_3$ are reported. We find a substantially ionic electronic structure for ${\mathrm{NaAlH}}_4,$ which emphasizes the importance of solid-state effects in this material. The relaxed hydrogen positions in ${\mathrm{NaAlH}}_4$ are in good agreement with the recent experiment. The electronic structure of ${\mathrm{AlH}}_3$ is also ionic. Implications for the binding of complex hydrides are discussed.